Method of making fuel briquettes, and binding agent suitable therefor



Patented July 9, 1940 PATENT OFFlCE METHOD OF MAKING FUEL BRIQUETTES,

AND BINDING AGENT SUITABLE THERE- FOR Andor Futo, Budapest, Hungary, assignor to Ellis Corporation Patents & Investments Limited,

London, England No Drawing. Application March 10, 1939, Serial No.'261,119. In Hungary March 16, 1938 5 Claims.

This invention relates to the production of smokeless fuel briquettes, more particularly from coal dust, having improved water-resisting properties.

According to the present invention, waterproof fuel briquettes are prepared by briquetting the fuel with employment as binding agent of dried and ground boiled or steamed potatoes together with bitumen material, and then roasting (i. e. dry heating) the briquettes at temperatures within the range YO-300 C. until they acquire high durability and resistivity towards water.

The briquettes prepared by the method of the present invention have been found to have a resistivity towards the action of water which is superior to that possessed by briquettes made by the methods heretofore known. The reason for this is thought to be somewhat as follows. By employing a meal which has been obtained by boiling or steaming potatoes, drying them, and then binding the fuel particles together.

grinding them for preparing the binding agent, it is ensured that the latter contains, besides the starch of the potatoes, more particularly also the albumen of the potatoes. When now the briquette containing such binding agent is dry heated to temperatures of 70300 C. the albumen wagulates, and may be eventually partly or whol- 1y cokes, whilst at the same time the bitumen material distils and disseminates throughout the briquette, with the result that an odourless, smokeless and waterproof emulsion is produced of the coagulated albumen and the bitumen and/or distillation products thereof which is distributed throughout the bulk of the briquette, It will thus be seen that this binding effect is obtained in addition to the binding action due to the starch itself in conjunction with the bitumen material, so that particularly high durability and resistivity to the action of moisture is imparted to the briquettes by the method provided by the invention.

There are other minor advantages attending the method of the present invention. For example, potato meal from boiled or steamed potatoes together with bitumen material forms a cheaper binding agent than the uncooked kinds of potato meal, and further its use practically eliminates any tendency of mould formation on the finished briquettes.

In carrying out the method provided by this invention the heating of the shaped briquettes is effected preferably with progressive, e. g. stepwise, rise in temperature, the maximum temperature not exceeding 300 C. It is preferred to carry out the heating to a temperature which is approximately the fusion temperature of the bitumen material. The heating may be conveniently effected in flue gases. As already mentioned the dry heating of the briquetted fuel raises the strength of the briquettes and imparts to them also an extrely high water-resistivity.

The following examples illustrate modes of carrying out the present invention.

Example 1 100 kg. of Hungarian Pcser mineral coal dust having a grain size of 0 to 5 mm. was bound to briquettes by means of 4% by weight of binder; the binder consisted of bituminous substances e. g. bitumen, together with flour from boiled or steamed and ground potatoes, having substantially finer grains than the average grain size of the coal being briquetted, so that the grains of the meal after the admixture ensheath the coal grains as far as possible and do not wedge in as grains between the coal grains. The usual malaxing was effected by means of superheated steam, as a result of which the potato flour became pastified. Pressing to briquettes was then carried out under a pressure of approximately 250 kg./cm briquettes was carried out in a current of flue gases at a maximum temperature in the proximity of the melting point of the bituminous substances with careful and gradually increasing heating, as a result of which briquettes were obtained which answer to practical requirements as regards strength and stability towards water.

The mixing of the potato flour with the bitumen material may be carried out in any desired manner and in any desiredphase of the preparation of the substance being briquetted which is suitable for the purpose. A simple procedure is to mix the meal of boiled or steamed potatoes and the ground bitumen product, more particularly pitch, in the dry state and to use the mixture of these two powders as binding agent. In order to introduce the binding agent into the coal variety being briquetted the known sprinkle or spray method may be employed; the procedure is then such that first of all meal prepared from boiled or steamed potatoes is admixed as binding agent with the dust of the coal to be briquetted and thereupon the mixture is sprayed or sprinkled with the fused bitumen material.

The binding agent according to the invention advantageously contains at most 50% or still more advantageously at most 20% of bitumen. The invention consequently enables the quantity of The subsequent heating of the.

bitumen heretofore used, and which was well known to be disadvantageous on account of the soot formation and deposition caused by it, to be reduced to a comparatively small fraction.

Example 2 The dust from 100 kg. of Hungarian Pcser mineral coal having a maximum grain size of 5 mm. was briquetted with 2.5% by weight of binding agent. The binding agent had the following composition: '70%, that is to say 1.75 kg. of powder obtained from boiled or steamed and ground potatoes plus 30%, that is to say 0.75 kg., of bitumen. The potato powder and the ground product from the bitumen were previously uniformly mixed, and then this binding agent mixture was admixed with the coal dust. The usual malaxing of the thus prepared materialiwas carried out before the pressing operation at a temperature of about 100 C. by means'of superheated steam, under the action of which the po tato meal pastified but the bitumen melted. Pressing was carried out in the usual way with employment of a pressure of 250 kg./cm The briquettes obtained in this way, weighing about 300 g., were then subjected to a drying roasting in flue gases of approximately 250 C., by means of which the briquettes were carefully and stepwise heated to the maximum roasting temperature in accordance with the counter current principle. After the cooling down the strength and stability to water of the resulting briquettes were practically equal to the corresponding properties of briquettes prepared with 6-8% by weight of pitch, and furthermore they were quite smokeless.

What Iclaim is:

1. A method of preparing waterproof, smokeless fuel briquettes, more particularly from coal dust, consisting in briquetting the fuel with employment of dried and ground boiled or steamed potatoes together with bitumen material as binding agent, and roasting the briquettes over a temperature range of 70 C., to not above 300 C., until they acquire high durability and resistivity towards water.

2. A method as claimed in claim 1 in which the roasting of the briquettes is carried out with stepwise rise in temperature.

3. A method as claimed in claim 1 in which the minimum roasting temperature of the briquettes is, approximately the fusion temperature of the bitumen material used.

4. A method of preparing waterproof smokeless briquettes, more particularly from coal dust, consisting in mixing dried and ground, boiled or steamed potatoes together with the fuel, spraying the mixture with fused bitumen material, briquetting the mixture, and roasting the briquettes over a temperature range of 70 C., to not above 300 C., until they acquire high durability and resistivity towards water.

5. A method as claimed in claim, 1 in which the bitumen content of the binding agent does not exceed 50%.

ANDOR FUTO. 

